Disequilibrium for Ca during growth of pelitic garnet

Compositional zoning in hundreds of almandine-rich garnets in amphibolite by facies micaceous quartzites from the Picuris Range, north-central New Mexico USA, indicates that although Mn, Mg and Fe achieve chemical equilibrium at hand-sample scale during garnet growth, Ca does not. Instead, Ca concentrations at the surface of growing garnets appear to depend strongly on kinetic factors that govern the local chemical environment, yielding disequilibrium for Ca at scales larger than the region immediately surrounding an individual porphyroblast. Detailed zoning profiles were obtained for 371 garnet crystals in a small volume of a single sample of garnetiferous quartzite, and core analyses were made of 97 additional crystals. Each analysis was made on a section that passed precisely through the morphological centre of the crystal, located by means of 3-D imagery from computed X-ray tomography. The data reveal strong correlations between crystal size and concentrations of Mn, Mg and Fe (but not Ca) in garnet cores; a relationship between crystal size and isolation; rigorous cross-correlations among concentrations of Mn, Mg and Fe (but not Ca); and systematic variations in Ca concentrations as a function of crystal size and core composition that are anomalous in comparison to the behaviour of the other divalent cations. We interpret these observations as the result of thermally accelerated diffusion-controlled garnet growth, in circumstances that promoted rapid intergranular diffusion and thus rock-wide equilibration of Mn, Mg and Fe, but that prevented equilibration at similar scale for Ca because of its more sluggish intergranular diffusion. The anomalous behaviour of Ca is made evident in these garnets by the presence of sharp spikes in Ca concentration, which are demonstrably not a consequence of any simultaneous rock-wide event, such as a change in pressure, temperature, or some other intensive parameter. Instead, Ca concentrations probably reflect the local extent of reaction in the immediate vicinity of each porphyroblast. To the degree that such kinetic factors introduce departures from chemical equilibrium for Ca, thermobarometric estimates that involve grossular contents of pelitic garnet will be in error.     

博斯腾湖的水盐平衡与矿化度

博斯腾湖曾是中国内陆区最大的淡水湖，因人类活动影响约在１９６８年演变为微咸水湖。本文依据湖泊水平衡太矿化度基本原理，结合博斯滕湖实际，分析计算了该湖各个时期的水盐平衡与矿化度；经推地整理，提出了预测矿化度的计算式，经检验与实测值基本吻合。     

流体的热力学前缘研究

总结了当前国内外关于流体的热力学前缘研究领域如下：（１）流体体系的ｐ－Ｖ－Ｔ－ｘ相关系研究，主要对象是Ｈ２Ｏ－ＣＯ２－盐类多组分体系高温高压下相图的实验和理论研究。（２）矿物在流体中的溶解度及溶解后在流体中溶解类型的形式和热力学性质——平衡常数（或Ｇｉｂｂｓ自由能）及各种偏摩尔性质的研究。（３）流体热力学模型化研究，已研制出大量的计算机软件，包括多种矿物、溶解类型的热力学数据库和模拟热液平衡、矿物溶解性质、反应路径和水—岩相互作用的实用程序。（４）超临界流体的相关系和化学反应等有许多特殊的性质，对认识地球内部的演化将有重要意义。（５）新技术新方法的发展，使分析单个矿物包裹体成分变成了现实。     

High Pressure-Differential Thermal Analysis and Ultrasonic Wave Amplitude Analysis of Ice-Water Equilibrium at 1.5-5.0GPa

Water is the most active component in all geological systems.It has an important effect on the physical properties of minerals and melts.It also plays a key role in the evolution of the Earth.Accurate thermodynamics data on water are currently confined to pressures below 1.0GPa and temperatures below 900℃.Presented in this paper are new data available on the P-T properties of water at pressures up to 5.0GPa,develoged from differential thermal analysis and ultrasonic wave amplitude analysis.It has been found that there may exist another ternary point at 3.0GPa and that ultrasonic wave amplitude change of ice-water transition shows two inflection points above 2.0GPa, consistent with the two peaks of differential thermal curves above 2.0GPa .It may be a new phenomenon which needs further study.     

从天山乌鲁木齐河源1号冰川变化估计近百年来该地区夏季升温

通过冰川波动历史来揭示气候变化是一种重要的方法。然而，以往有关这一方面的研究大都是一些定性的。文章试图依据冰种变化来定量的研究气候变化，并且通过近百年来天山乌鲁木齐河源１号冰川的变化，揭示出本世纪以来该河源地区夏季气温上升约０．２３￣０．２５℃，同时，对于该冰川不同长度规模时的气候敏感性也进行了讨论。     

AN APPARENT TEMPERATURE MODEL BASED ON THERMAL EQUILIBRIUM

In this paper,a comprehensive analysis and review of the advances in the research of human body comfort degree is made.Based on the studies of human thermal equilibrium theories contributed by previous researchers,different apparent temperature models corresponding to different environments are set up in accordance with the current situation and the characteristics of metabolism in different groups of people in China.After case studies and comparison with present dominant human body comfort degree statistical models,it is proved that the apparent temperature models have high rationality and wide adaptability.Furthermore,the comfort scaling standard according to apparent temperature is suggested,which is suitable for the middle latitude regions in China.     

钱家店铀矿床U-Ra平衡系数特征研究

本文探讨了可地浸砂岩型铀矿U-Ra平衡系数的计算方法，研究了钱家店砂岩型铀矿床U-Ra平衡系数的变化特征。这些成果为钱家店铀矿床放射性测井数据的修正、矿体边界的确定、铀矿资源量的计算提供了科学依据。     

红砂岩高陡岩质边坡稳定性分析及治理

充分利用边坡失稳前自身抗滑能力进行高陡边坡治理，结合工程实例，提出了主动性公路边坡治理的思路。分别利用极限平衡法和有限元数值法，综合考虑了两种方法的优缺点，对红砂岩高陡边坡进行了全面的稳定性分析，并针对性地提出了经济合理的治理方案。     

Modélisation morphodynamique cross-shore d'un estran vaseux

Numerical experiments were performed to simulate the profile evolution of an intertidal mudflat with a 1D cross-shore morphodynamical model. First, the hydrodynamical forcing is a cross-shore tidal current due to semi-diurnal variations of the free surface elevation at the open boundary. Further, considering the conservation of the action density of surface gravity waves, a wave height (and resulting bottom shear stress) calculation is added to the morphodynamical model. Results of the numerical experiments show that the shape of the profile reaches equilibrium. The mudflat progrades continually when the forcing is tide only, whereas it can be steady under the simultaneous action of tide and waves. To cite this article: B. Waeles et al., C. R. Geoscience 336 (2004).     

Two contrasted P–T–time paths of coronitic metanorites of the French Massif Central: are reaction textures reliable guides to metamorphic histories?

Metanorites from two eclogitized metagabbros of the Hercynian French Massif Central preserve coronitic textures of hornblende, garnet, quartz and/or kyanite produced at the expense of the primary magmatic assemblage orthopyroxene and plagioclase. Using a petrogenetic grid in the CFMASH system, two possible P–T evolutions for the origin of the coronas are evaluated. The sequence of reactions involving the formation of Hbl (–Ky) ± Grt and Qtz coronitic assemblages is consistent with an isobaric cooling at high pressure (c. 1–2 GPa) under hydrated conditions. However, this P–T path, inferred by using only petrographical observations, is inconsistent with the geochronological constraints: emplacement of the gabbro at 490 Ma and high‐pressure metamorphism at 410 Ma. In order to reconcile petrographical observations with geochronological constraints, we propose a discontinuous two‐stage evolution involving a change in water activity with time. (1) Emplacement and cooling of the norite at low pressure under anhydrous conditions, at 490 Ma. (2) During the Hercynian orogeny, the norite experienced an increase in pressure and temperature under fluid‐present conditions. Adding water to the system implies a dramatic change in the petrogenetic grid topology, restricting the orthopyroxene–plagioclase assemblage only to high temperatures. Therefore, the breakdown of the unstable magmatic assemblage, through apparent retrograde reactions, occurred along the prograde P–T path which never crossed the equilibrium boundaries of these reactions.